Planar Zn-Ion Microcapacitors with High-Capacity Activated Carbon Anode and VO2 (B) Cathode.

ABSTRACT

The downsizing of microscale energy storage devices plays a crucial role in powering modern emerging devices. Therefore, the scientific focus on developing high-performance microdevices, balancing energy density and power density, becomes essential. In this context, we explore an advanced Microplotter technique to fabricate hybrid planar Zn-ion microcapacitors (ZIMCs) that exhibit dual charge storage characteristics, with an electrical double layer capacitor type activated carbon anode and a battery type VO2 (B) cathode, aiming to achieve energy density surpassing supercapacitors and power density exceeding batteries. Effective loading of VO2 (B) cathode electrode materials combined with activated carbon anode onto confined planar microelectrodes not only provides reversible Zn2+ storage performance but also mitigates dendrite formation. This not only results in superior charge storage performance, including areal energies of 2.34 µWh/cm2 (at 74.76 µW/cm2) and 0.94 µWh/cm2 (at 753.12 µW/cm2), exceeding performance of zinc nanoparticle anode and activated carbon cathode based ZIMCs, but also ensures stable capacity retention of 87% even after 1000 cycles and free from any unwanted dendrites. Consequently, this approach is directed toward the development of high-performance ZIMCs by exploring high-capacity materials for efficient utilization on microelectrodes and achieving maximum possible capacities within the constraints of the limited device footprint.